Theftproof lamp



W. 5.. ANDERSON Dec. 6, 1927.

THEETPROOF LAMP Filed May '11, 1925 FI GJ Q WALDE'MAR a 55 INVENTOR E. ANDERSO N 4 Y ATTORNEY Patented Dec. 6, 1927.

UNITED. STATES 1,651,357 PATENT OFFICE.

WALDEMAR ENOCH ANDERSON, OF MONTCLAIR, NEW JERSEY, AS SIGNOR TO WESTING- HOUSE LAMI? COMPANY, A CORPORATION OF PENNSYLVANIA.

THEFTPBOOF LAMP.

Application filed May 11, 1925. Serial No. 29,303.

with electric incandescent lamps used inpublic places, such as railroad stations and also in factories and warehouses, etc., results in considerable loss of such lamps through theft. Attempts have been made to provide specially constructed sockets as well as specially constructed bases which were intended to operate to either prevent the removal of a lamp from a socket by means other than a special instrument or requiring the breakage of a bulb in order to remove the base from a socket.

The use of a lock which requires a special type of instrument for removing a bulb from a socket is not desirable, nor has it been found practical to break the bulb. The breaking of a bulb is an obvious disadvantage inasmuch as it can be'appreciated that the flying glass and ragged edges, often cause personal injury to the one removing the lamp as is necessary when the same has burned out.

An object of the presentdnvention is to provide a base for an incandescent electric lamp of simple and inexpensive construction which may be readily applied to and locked in the ordinary lamp socket and which may J be readily removed without breaking the bulb of the lamp but not without destroying the usefulness of the lamp.

Another object if the lnvention is to provide a lamp base which cannot be removed except by first breaking one of the electrical conductors.

A further object, of the invention isto.

provide a lamp base having a member so associated therewith as to not, to prevent the rotation of the base when the same is screwed in a socket but which will offer resistance to an opposite rotation of the base for theremoval of the lamp. 4

A still -.further object of the invention is to provide effective means for locking a lamp in a socket and simple and convenient means for unlocking the locking means.

Other objects and advantages will appear as the description proceeds.

Although the invention will be described herein in connection with an incandescent lamp, it is understood that it is equally ap--' plicable to other types of screw plugs or to bases in which a movable member is adapted to lock the base in place and in which it is desirable to unlock the same.

An embodiment of the present invention may comprise the ordinary type of threaded base as applied. toan incandescent electric lamp. The base may be provided with the usual end contact connected to one of the lead wires of the lamp. The base may be provided with a lateral aperture from which may project a spring member or barb adapted to normally move the pointed end thereof toward theperiphery or exterior of the base, the barb being positioned so as to point in the direction opposite to that in which the lamp is screwed during its insertion in a socket. The barb-being normally pressed against the socket will, by reason ofits sharpened point, engage therewith upon a reverse movement of a base and prevent further movement for the removal of the lamp,

The present invention provides means for v removing the barb from contact with the wall of a socket and may comprise a wire secured to the spring member and adjacent to the free end thereof and to-a leading-in conductor of the lamp. This wire may-be clamped or suitably attached to a leading-in conductor and may then extend over the upper edge of the base and to the exterior thereof and the free end of the wire may be suitably soldered or welded to the base in a manner similar to that practiced for the usual leading-in conductor.

When a lamp has been screwed into a socket, the spring member-prevents its un- The invention will be more fully understood by reference to the accompanying drawing, in which Fig. 1 is an elevational view of an incandescent lamp having a base constructed in accordance with the present invention;

Fig. 2 is a plan view of the base shown in Fig. 1 but slightly in perspective, the bulb of the lamp being removed;

Fig. 3 is a view taken substantially on line III-III in Fig. 1 but with the bulb removed;

Fig. 4: is a side view of a lamp partly .in section and screwed into a socket;

Fig. 5 is a transverse sectional view of a base Swithout a bulb therein) and showing a flexib e member pulled taut to release a spring-member from engagement with a socket; and

Fig. 6 is a fragmentary view showing a portion of the device somewhat modified to provide a flexible member or latch string of non-conductive material.

As illustrated in Fig. 1 the present invention may be applied to an incandescent lamp comprising a bulb 10 having a base 11 of the usual threaded type cemented thereto. The base may be provided with an aperture 12 which as illustrated (see Fig. 1) is provided by bendin a portion of the wall of the shell to form a ead13 (see Fig. 5). It is obvious that the aperture 12 may be punched only large enought to permit the obtrusion of the end of the barb 15. A spring member or dog 14 may be provided of a relatively hard and highly elastic metal such as steel and may be provided with a sharpened end or barb 15. The spring member may be cylindrical and of such dimensions as to be applicable for seating in a pgiral groove provided in the shell of the se by the formation of the threads thereon. The end 15 of the spring member may be positioned to normally project through the aperture 12. The opposite end 16 of the member may be disposed so as to engage with the bead 13 which forms an abutment and resists movement of the spring member when the same is serving as a lock, the end 16 may however be further secured to the base by solderin weldin Or the like. The bead may, if esirableje omitted.

e spring member 14. will, therefore, when a lamp is screwed to .a socket 17, engage with the'wall 18 thereof and by reason of the barb will bite or plow into the wall of the socket as shown in Fig. 3 upon an opposite rotation of the base, thus preventing a removal of the lamp from the socket.

For the urpose of conveniently releasing the spring member or dog, a flexible member in theform of a wire 19 may be provided and secured at one end 15 to the member 14. On the wire 19 at a suitable distance from the spring member, a leading-in conductor 22 of the lamp may be secured either by clamping or slightly soldering sufiiclent to make a good electrical contact but making a frangible connection. The conductor 22 should be of such length as to permit rupture of this connection when the member 19 is pulled taut. The flexible member or wire 19 may then pass out through a notch 23 at the upper portion of the base and may extend partially. therearound and be soldered thereto at 24 (see Figs. land 3). A suitable sleeve 20 may be provided to incase a portion of the flexible member 19 which passes through the cement for securing the base to the bulb, in order to ermit a free movement of the member 19 which might otherwise ad here to the cement.

A leading-in conductor 20 which is connected to an axially disposed contact 21 on the base may be provided with an insulating sleeve 22 to prevent shortcircuiting if the flexlible member 19 is moved in contact therewit 1.

When the member 19 has been soldered to readily be screwed into a socket and held therein by engagement of the spring member with the wall of the socket. A lamp,'therefore, is locked against removal and may be left until the same has burned out or become inefficient at which time the member 19 may be broken by means of a pocket knife or like instrument from its soldered connection to the outside of the base and a pull exerted thereon- This pull results, first in a separation between the conductor 22 and the flexible member 19 and a continued pull moves the end 15 of the spring member 14' to disengage the same with the wall of the socket and permit a removal of the lamp therefrom. It will be appreciated that the wire or flexible. member 19 is similar in function to a latch string.

The connection between the member 19 and the leading-in wire 22, however, is such that a pull upon the latch string or wire is opposed by the lower edge of the bulb with which the leading-in wire 22 engages, thus making it necessary to break the connection between the flexible member 19 and the leading-in wire 22 before the slack 25 can be taken up and a pull exerted upon the spring member14.

It will be understood that. the flexible member 19 may, as shown in Fig. 6, be comprised of twosections 30 and 31. The section 31 may be frangibly secured to the leading-in wire 22 and the section may be permanently secured to the section 31 which is fastened to the end '15 of the spring member 14. The section 30 may consist of a string of non-conductive material. An end 32 of the string may extend outwardly from the base and may be provided with a tab 33 or other member'convenient to be gripped between the fingers. The string may be of suflicient strength so that when the tab is pulled, the flexible member will break away from the leading-in wire 22 and the spring 14 may be moved to release the base. It will be seen that by reason of this construction, the releasing mechanism may be actuated without necessity of breaking the string from a connection to the outside of the base as in the case of a lamp constructed as previously described. When a wire is used. as a latch-string in the above mentioned construction, it is more desirable to anchor the same to the bulb, but in the case of a limp or flexible member such as the section 30 the same may hang over the edge base.

of the socket ready for use to release the The leading-in wire 22 being connected, to the conductive section 31 of the flexible member and to the spring 14 is in electrical contact with the base for the passage of current, thus making it possible to employ the non-conductive section 30.

The present invention makes it possible to provide a lamp of simple construction whic may readily be locked from surreptitious or unauthorized removal without destruction but which may be readily replaced by an- 1 otherlamp.

Although a preferred embodiment of the invention is shown and described herein, it is to be understood that other modifications may bemade which, may fall within the spirit and scope of the appended claims.

What is claimed is:'

1. An incandescent electric lamp having a base comprisinga-threaded shell, an internal spring member adapted to extend through a wallof said shell, said member being disposed to permit a rotation of said base into a socket and to engage the socket to prevent an opposite rotation of the base, means associated with said spring member and extending exteriorly of the lamp, said means being normally accessible and manually operable to flex said spring member to disen-. gage the same with saidsocket and permit a removal of the base there 2. An incandescent electricfliifiip-having a base comprising a sprin member disposed about the'inner surface is ereof,;anaperture in the wall of said base to permit the projection of an end of said spring member, said member being constructed to slidably engage the wall of a socket whena base is screwed therein and to plow into the socket upon an opposite rotation to said base to flexible member having 0 lead wire frangibly secured to, and held sub- 120 lock the same in the socket and a latch member associated with said spring and accessible externally of the base for manual operation to release the same for removal from the socket.

3. An incandescent electric lamp having a base comprising a spring member disposed about the inner surface thereof, an aperture in the wall of said base to permit the projection of an end of said spring member, said member being constructed to slidably engage the wall of a socket when a base is screwed therein and to plow into the socket upon an opposite rotation to said base to lock the same in the socket, a latch member for releasing said base associated with said spring and frangibly connected to one of the lead wires of said lamp, said latch member being disposed externally of the lamp and accessible for manual actuation.

4. An incandescent electric lamp having a threaded base, a spring member disposed in said base for locking the same in a socket, a flexible member having one end attached to the free end of said spring-member, the opposi te end being secured to the outer surface of said base and a leading-in wire of said lamp frangibly connected to said flexible member.

5. An, incandescent electric lamp having a threaded base comprising a shell, an aperture in the wall of said shell, a spring-member disposed within said shell and having a pointed end projecting through said aperture in a direction opposite to the direction of rotation during insertion into a socket, a flexible member having one end secured to said projecting end, the opposite end of said flexible member being'secured to the outer surface of said base and a lead wire electrically but frangibly connected tosaid flexible member.

6. An incandescent electric lam having a ture in the wall of said shell, a spring-member disposed within said shell and having a pointed end projecting through said aperture in a direction opposite to the direction of rotation during inserti into a socket, a h d f d 'nd seplured to t e ro'ectinggen o sai 'srin ,t e0 0- site tend of said flexible mgmbe r being ecured to the outer surface of said base, a

stantially taut by said flexible member.

7. An incandescent electric lamp having a bulb, a threaded base comprising a shell secured to said bulb, an aperture in the wall of said shell, a spring-member disposed within said shell and.having a pointed end projecting through said-aperture in a'direction opposite to the direction of rotation during insertion into a socket, a flexible member having one end securedto the projecting end of said spring, the opposite end of said flexible member being secured to the outer surface of said base, a lead wire frangibly connected to said flexible member and held with a portion thereof adjacent to said connection in close proximity to the lower end of said bulb and a slack portion in said flexible member between said frangible connection and said spring member.

8. An incandescent electric lamp having a base comprising a threaded shell, a spring member constructed for disposition in a groove provided by the threads of said shell, means for securing an end of said member to said shell, an aperture in the Wall of said shell to permit the projection of the free end of the spring in a direction opposite to the direction of rotation during insertion into a socket, a flexible member having one end secured adjacent to the free end of said sprin -member, the opposite end of said fiexib e member being soldered to the outer surface of said shell and a leading-in conductor electrically connected to said flexible member.

9. An incandescent electric lamp having a base comprising a hollow member, leadingin conductors extending into said base, a spring-member disposed within and having an end projecting from said'base to lock the base in position when screwed in a socket, a flexible member comprising a conductive section and a non-conductive section connected to said spring member, one of said leading-in conductors connected to the conduetive section of said flexible member, the

non-conductive section extending exteriorly of the base.

10. An incandescent electric lamp having a base, a member adapted to lock the base to a socket, leading-in conductors extending into said base, a flexible member comprising conductive and non-conductive sections, said conductive section being attached to the locking member and to one of said leadin in Wires, the non-conductive section exten ing from the base.

In testimony whereof, I have hereunto subscribed my name this Qthday of May, 1.925.

\VALDEMAR ENOCH ANDERSON. 

